1. FIELD OF THE INVENTION
The field of the invention is a valve operating system of an internal combustion engine, which has a plurality of valve operating means disposed for opening and closing engine valves, a connection means movable for integrally connecting the valve operating means, and a driving means for driving said connection means.
2. DESCRIPTION OF THE PRIOR ART
Valve operating systems of the above mentioned type are known, for example, from Japanese Patent Publication Kokai No. 124817/88 and the like.
In case of such a known valve operating system, a connection switchover mechanism for selectively connecting and releasing connection between a plurality of rocker arms as the afore-mentioned valve operating means is provided and it comprises a plurality of pins which are abutted against each other in coaxial arrangement, the pins including a switchover pin exposed at one axial end surface thereof to a hydraulic pressure chamber and movable between a position connecting adjacent rocker arms and another position releasing such connection and a regulating pin with a return spring interposed between the regulating pin and one rocker arm, the return spring exerting a spring force to the regulating pin so as to urge it toward the one axial end side.
In such a valve operating system, however, the connection switchover mechanism may encounter a problem that the switchover pin is locked against movement and therefore it is desired to detect and deal with such an operationally locked condition of the connection switchover mechanism. Formerly proposed systems, however, do not have means for detecting a locked condition of the connection switchover mechanism.